1. Field of the Invention
This invention relates generally to locking systems for preventing unauthorized entry into the interiors of enclosures containing electrical equipment therein, and pertains more particularly to a two-step locking system in which a padlock has to be first removed from a unit mounted on the enclosure in order to gain access to a special locking bolt concealed within the unit which bolt must then be removed in order to gain entry to the enclosure.
2. Description of the Prior Art
In order to protect various types of electrical equipment, such as switchgear, metering, controls and protecting devices, the electrical utility industry has required appropriately designed enclosures, such as upright pedestals, cabinets and terminal boxes, the particular enclosure depending largely upon the type of electrical equipment to be housed and its place of installation.
Both single and double locking systems have been employed. The most common single locking system has made use of a common hasp and staple type of fastener, involving a conventional padlock. When a double locking system is used, the secondary fastener is in the form of a penta-head bolt involving the recessing of a five-sided bolt head so that a special wrench is needed in order to obtain access to the equipment housed within that particular enclosure.
The difficulty with the alluded to prior art dual locking system resides in that each fastener is completely exposed to view. Tampering is made comparatively easy because an unauthorized person can visually ascertain what is needed in the way of tools to obtain entry into the enclosure. Also, such an exposed locking system is vulnerable to adverse weather conditions. Still further, it is needlessly unattractive. Furthermore, the installation of a dual locking system involving both a hasp-type fastener and a five-sided bolt-type fastener increases the manufacturing cost of the enclosure.